Previous studies on this project have shown that allergy to Mountain Cedar (Jupineros sabinoides) pollen is associated with HLA-DR7 and that lymphocytes from subjects with skin test reactivity to cedar pollen antigen (CPA) proliferate vigorously when cultured with whole extracts of the pollen. In these studies CPA allergy is viewed as a model of HLA-associated disease with the advantage that the antigen causing the disease is available to test the mechanism that determines the HLA association. This is in contrast to other HLA-associated diseases such as rheumatoid arthritis or insulin-dependent diabetes mellitus in which, because the causative antigens are unknown, such experiments cannot be performed. T cell clones that proliferate when cultured with CPA have been produced and their HLA restriction will be investigated. The question we wish to answer is whether the HLA antigen associated with the disease in the population is preferentially used by T cells to recognize CPA. Lymphocyte-stimulating fractions of CPA have been prepared and their amino acid sequence is being determined. Peptides based on the structure will be used to investigate the immunodominant epitopes that trigger the response of different types of human T cells. In additional experiments, the production of CPA-specific IgE and IgG antibody production will be correlated with the profiles of cytokines produced by T cells from allergic and non-allergic subjects. To further analyze the T cell response, the variable segments of the T cell receptors utilized by CPA-specific T cells will be analyzed by a quantitative polymerase chain reaction (PCR) and by nucleotide sequencing. These experiments should shed light on the fundamental question of why, although equally exposed, some individuals develop allergy and others do not.